Tumor Innervation Research Articles

MAOA promotes prostate cancer cell perineural invasion through SEMA3C/PlexinA2/NRP1–cMET signaling

Perineural invasion (PNI), a pathologic feature defined as cancer cell invasion in, around, and through nerves, is an indicator of poor prognosis and survival in prostate cancer (PC). Despite widespread recognition of the clinical significance of PNI, the molecular mechanisms are largely unknown. Here, we report that monoamine oxidase A (MAOA) is a clinically and functionally important mediator of PNI in PC. MAOA promotes PNI of PC cells in vitro and tumor innervation in an orthotopic xenograft model. Mechanistically, MAOA activates SEMA3C in a Twist1-dependent transcriptional manner, which in turn stimulates cMET to facilitate PNI via autocrine or paracrine interaction with coactivated PlexinA2 and NRP1. Furthermore, MAOA inhibitor treatment effectively reduces PNI of PC cells in vitro and tumor-infiltrating nerve fiber density along with suppressed xenograft tumor growth and progression in mice. Collectively, these findings characterize the contribution of MAOA to the pathogenesis of PNI and provide a rationale for using MAOA inhibitors as a targeted treatment for PNI in PC.

Neurons Release Serine to Support mRNA Translation in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) tumors have a nutrient-poor, desmoplastic, and highly innervated tumor microenvironment. Although neurons can release stimulatory factors to accelerate PDAC tumorigenesis, the metabolic contribution of peripheral axons has not been explored. We found that peripheral axons release serine (Ser) to support the growth of exogenous Ser (exSer)-dependent PDAC cells during Ser/Gly (glycine) deprivation. Ser deprivation resulted in ribosomal stalling on two of the six Ser codons, TCC and TCT, and allowed the selective translation and secretion of nerve growth factor (NGF) by PDAC cells to promote tumor innervation. Consistent with this, exSer-dependent PDAC tumors grew slower and displayed enhanced innervation in mice on a Ser/Gly-free diet. Blockade of compensatory neuronal innervation using LOXO-101, a Trk-NGF inhibitor, further decreased PDAC tumor growth. Our data indicate that axonal-cancer metabolic crosstalk is a critical adaptation to support PDAC growth in nutrient poor environments.

Abstract LB-B17: Uncovering novel cancer therapeutics using the Exoneural Medicines Platform: The role of innervation in cancer

Abstract Peripheral nerves were first described as a component of tumors in the late 19th century. In the mid-20th century early preclinical studies indicated that tumor cells could recruit innervation from spinal cord ganglia and that stress promotes tumorigenesis. Within the last 10 years improvements in technologies allowing neuronal tracking and regulation of neuronal function have uncovered a role for both autonomic and sensory innervation in multiple tumor types. Initial studies have implicated this biology in prostate, pancreatic, gastric and breast cancer (among others) and point to a role for nerves in initiation, maintenance and metastasis of tumors. The stimulation of tumor cell growth by neural growth factors, the recruitment of neurites by tumor cells, the invasion and migration of tumor cells along nerves (perineural invasion), and the role of innervation in driving tumor angiogenesis are just a few examples of how peripheral nerves interact with the tumor microenvironment. Indeed, an argument could be made that innervation of tumors should be considered a hallmark of cancer. We describe here a biological platform that can define and decode the role of neural signaling in cancer. This platform, which we call Exoneural Medicines Platform ™, has 6 technical components: 1) co-culture models of primary neurons with both tumor and immune cells, 2) advanced imaging modalities to define the neural component of tumors, 3) AAV and transgenic tools that allow regulation of neurons proximal to tumors in vivo and in vitro, 4) neural-focused functional genomics, 5) neural-focused bioinformatics, and 6) a neuropharmacopeia compound library for probing relevant biological pathways and identification of advanced starting points for drug discovery. We show here how the platform is being employed to characterize this exciting new space in cancer biology and to identify new drivers of disease. Citation Format: Shan Lou, Alexandria Fink, Jay Wang, Jesse Turner, Monica Thanawala, Garmen Yuen, Alexandra Lantermann, Jenny Shu, Hongyue Dai, Pearl Huang, Jonathan Hurov. Uncovering novel cancer therapeutics using the Exoneural Medicines Platform: The role of innervation in cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr LB-B17. doi:10.1158/1535-7163.TARG-19-LB-B17

Exosomal Induction of Tumor Innervation.

The naïve view of tumors as isolated islands of rogue cells has given way to a deeper understanding of cancer as being closer to a foreign organ. This "organ" contains immunologic, vascular, and neural connections to its host that provide not only mechanisms for disease progression but also opportunities for therapeutic intervention. The presence of nerves within tumor tissues has long been appreciated. However, a mechanistic understanding of how tumors recruit nerves has been slower to emerge. Tumor release of neurotrophic factors and axonal guidance molecules likely directs axons toward the tumor bed. Newly emerging data support a contribution of tumor-released exosomes in the induction of axonogenesis toward the tumor. Exosomes, small membrane-bound vesicles that carry a complex cargo (DNA, RNA, miRNA, lipids, and proteins), protect their cargo from the low pH of the tumor microenvironment. They also represent an efficient means of local and distal communication between the tumor and potentially innervating nerves. Likely, a combination of neurotrophins, guidance molecules, and exosomes work in concert to promote tumor innervation. As such, defining the critical components driving tumor innervation will identify new targets for intervention. Moreover, with a deepening understanding, tumor innervation may emerge as a new hallmark of cancer.

Genetic manipulation of autonomic nerve fiber innervation and activity and its effect on breast cancer progression.

The effects of autonomic innervation of tumors on tumor growth remain unclear. Here we developed a series of genetic techniques to manipulate autonomic innervation in a tumor- and fiber-type-specific manner in mice with human breast cancer xenografts and in rats with chemically induced breast tumors. Breast cancer growth and progression were accelerated following stimulation of sympathetic nerves in tumors, but were reduced following stimulation of parasympathetic nerves. Tumor-specific sympathetic denervation suppressed tumor growth and downregulated the expression of immune checkpoint molecules (programed death-1 (PD-1), programed death ligand-1 (PD-L1), and FOXP3) to a greater extent than with pharmacological α- or β-adrenergic receptor blockers. Genetically induced simulation of parasympathetic innervation of tumors decreased PD-1 and PD-L1 expression. In humans, a retrospective analysis of breast cancer specimens from 29 patients revealed that increased sympathetic and decreased parasympathetic nerve density in tumors were associated with poor clinical outcomes and correlated with higher expression of immune checkpoint molecules. These findings suggest that autonomic innervation of tumors regulates breast cancer progression.

Cancer exosomes induce tumor innervation

Patients with densely innervated tumors suffer with increased metastasis and decreased survival as compared to those with less innervated tumors. We hypothesize that in some tumors, nerves are acquired by a tumor-induced process, called axonogenesis. Here, we use PC12 cells as an in vitro neuronal model, human tumor samples and murine in vivo models to test this hypothesis. When appropriately stimulated, PC12 cells extend processes, called neurites. We show that patient tumors release vesicles, called exosomes, which induce PC12 neurite outgrowth. Using a cancer mouse model, we show that tumors compromised in exosome release are less innervated than controls. Moreover, in vivo pharmacological blockade of exosome release similarly attenuates tumor innervation. We characterize these nerves as sensory in nature and demonstrate that axonogenesis is potentiated by the exosome-packaged axonal guidance molecule, EphrinB1. These findings indicate that tumor released exosomes induce tumor innervation and exosomes containing EphrinB1 potentiate this activity.

Psychoneuroimmunology of Cancer - Recent Findings and Perspectives.

Gallen observed that psychosocial factors influence tumor incidence. Findings of the last decades have enabled us to understand the mechanisms and pathways responsible for this influence. Ader, Solomon, Besedovsky, and other pioneers of psychoneuroimmunology demonstrated that the nervous system can regulate the activity of immune cells. Based on their findings, the mechanisms via which psychosocial stressors potentiate tumor growth indirectly through inhibition of anti-tumor immune cells have been reported. Human tumor innervation, the presence of β-adrenergic receptors on tumor cells, and the stimulating effect of noradrenaline on tumor growth and metastasis development have revealed that psychosocial stressors have a direct stimulatory effect on tumor growth, mainly via sympathetic nerves. In recent years, the possibility of modulating signal transduction between the nervous system, immune system, and tumor cells, with the intention of inhibiting tumor growth and metastasis, has been intensively investigated. The aim of this review paper is to provide an overview of recent experimental and clinical findings from psychoneuroimmunological research, which reveal an increasingly complex link between stress and the onset and progression of tumor diseases and provide a basis for the introduction of new therapeutic approaches for the treatment of cancer patients. Some approaches tested in psychoneuroimmunological studies reported that they had inhibitory eff ects on cancer growth and used already clinically-approved drugs and psychological procedures, which may facilitate their application in oncology in the near future.

Sustained Adrenergic Signaling Promotes Intratumoral Innervation through BDNF Induction.

Mounting clinical and preclinical evidence supports a key role for sustained adrenergic signaling in the tumor microenvironment as a driver of tumor growth and progression. However, the mechanisms by which adrenergic neurotransmitters are delivered to the tumor microenvironment are not well understood. Here we present evidence for a feed-forward loop whereby adrenergic signaling leads to increased tumoral innervation. In response to catecholamines, tumor cells produced brain-derived neurotrophic factor (BDNF) in an ADRB3/cAMP/Epac/JNK-dependent manner. Elevated BDNF levels in the tumor microenvironment increased innervation by signaling through host neurotrophic receptor tyrosine kinase 2 receptors. In patients with cancer, high tumor nerve counts were significantly associated with increased BDNF and norepinephrine levels and decreased overall survival. Collectively, these data describe a novel pathway for tumor innervation, with resultant biological and clinical implications.Significance: Sustained adrenergic signaling promotes tumor growth and metastasis through BDNF-mediated tumoral innervation. Cancer Res; 78(12); 3233-42. ©2018 AACR.

An Adrenergic-Neurotrophin Feedforward Loop Promotes Pancreatic Cancer.

Stress-activated ADRB2 signaling promotes tumor innervation and PDAC development.

Settling a Nervous Stomach: The Neural Regulation of Enteric Cancer

The nervous system is emerging as a regulator of malignancy. In this issue of Cancer Cell, Hayakawa etal. demonstrate a feedforward signaling loop in which tumor-derived nerve growth factor promotes enteric tumor innervation, and recruited nerves drive cancer growth through acetylcholine-regulated Wnt signaling and stimulation of further NGF release.

Neurogenesis and angiogenesis in pancreatic cancer evolve concordantly via distinct transcriptional profiles

Introduction: Pancreatic cancer (PCa) is characterized by increased intratumoral nerve density and nerve hypertrophy. Conversely, the density of vessels and tumor perfusion in PCa were reported to be decreased when compared to normal pancreas, creating a hypoxic tumor microenvironment. This observation raises the question whether neurogenesis and angiogenesis in PCa behave oppositely or even suppress each other. Method: Human PCa specimens (UICC stages II-III, n = 57) were analyzed for the density of all (CD31+) vessels, all (S100+) nerves, and for the severity of neural invasion/NI and angioinvasion via cytokeratin-19 (CK19) triple immunolabeling. The transcriptomic profile of tumors with strong neurogenesis or strong angiogenesis was compared to those with little neuro- or angiogenesis via profiler PCR-arrays. Results: 41 out of 57 patients exhibited NI, whereas angioinvasion was detected in only one out of 57 patients. The mean vessel size and mean nerve size correlated positively (Sperman's coefficient r = 0.43, p = 0.0013), and the total area of nerves increased in parallel with the total area of vessels in the analyzed specimens (r = 0.28, p = 0.04). The frequency of NI increased in concordance with the amount of tumor innervation (r = 0.25, p = 0.059). There was no association between vessel density and NI. Patients with more pronounced tumor angiogenesis had greater intratumoral amounts of matrix metalloproteinase-9 (MMP9), beta-III-integrin, and TgfbetaR1, whereas patients with more neurogenesis exhibited intratumoral upregulation of interleukin-6, TrkA, Nr1I2, NGF, CX3CR1, and Neurotrophin-3. Conclusions: Angiogenesis and neurogenesis behave concordantly in PCa. Interleukin-6 and neurotrophic factors may be responsible for the remarkably high prevalence of NI in PCa.

Abstract 1062: Sustained adrenergic signaling promotes intratumoral innervation through BDNF induction

Abstract Mounting clinical and preclinical evidence supports a key role of sustained adrenergic signaling in the tumor microenvironment as a driver of tumor growth and progression. However, the mechanisms by which adrenergic neurotransmitters are delivered to the tumor microenvironment are not well understood. Sustained adrenergic signaling resulted in increased tumor growth and was correlated with a significant increase in intratumoral nerve density and norepinephrine in several orthotopic models of disease. These effects were completely abrogated by hexamethonium bromide (ganglionic blocker), but not by removal of the adrenal glands. To elucidate mechanism by which tumor cells induce nerve growth, we analyzed gene expression changes and found BDNF to be a key factor upregulated by catecholamine treatment. Treatment with different ADRB agonist and blockers determined that ADRB3 is required for the induction of BDNF. Use of cAMP and Epac agonist/antagonist demonstrated that this axis is required for catecholamine induced BDNF expression. Further analyses revealed that JNK exerts its control of BDNF expression through the regulation of AP-1. In various orthotopic models of disease, chronic stress significantly increased tumor growth and intratumoral innervation, an effect completely blocked by BDNF siRNA-DOPC nanoliposomes. Moreover, BNDF overexpression was sufficient to induce tumor growth and intratumoral innervation. Silencing of TrkB, BDNF receptor, on the host by murine BDNF siRNA-Chitosan nanoparticles blocked the effects of sustained adrenergic signaling on tumor growth and innervation. Additionally, inhibition of host TrkB activity in a transgenic TrkB Kinase-Switch mouse model inoculated with ovarian cancer cells showed that adrenergic induced tumor growth and innervation is mediated by the host TrkB. In cancer patients, high tumor nerve density was significantly associated with increased BDNF and norepinephrine levels, and worse overall survival. Collectively, these data describe a novel pathway for tumor neo-innervation with resultant biological and clinical implications. Citation Format: Guillermo N. Armaiz-Pena, Archana S. Nagaraja, Julie K. Allen, Nouara C. Sadaoui, Rajesha Rupaimoole, sherry Y. wu, Sunila Pradeep, Hee Dong Han, Behrouz Zand, Heather Dalton, Rebecca Previs, Morgan Taylor, Justin Bottsford-Miller, Lingegowda S. Mangala, Cristian Rodriguez-Aguayo, Mariela De Biasi, Gabriel Lopez-Berestein, Steve Cole, Susan K. Lutgendorf, Anil K. Sood. Sustained adrenergic signaling promotes intratumoral innervation through BDNF induction. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1062. doi:10.1158/1538-7445.AM2014-1062

Chemical sympathectomy suppresses fibrosarcoma development and improves survival of tumor-bearing rats

Both experimental and clinical data indicate that the sympathetic nervous system may affect the development of certain tumors. To test this, in the present study we combined in vivo and in vitro approaches to study the effect of the sympathetic nervous system on proliferation of BP6-TU2 fibrosarcoma cells. First, we investigated the effect of 6-hydroxydopamine-induced sympathectomy on tumor development and survival of tumor-bearing rats. One week after chemical sympathectomy, we injected the BP6-TU2 fibrosarcoma cells intraperitoneally into male Wistar rats. The sympathectomy significantly reduced the incidence of intraperitoneal tumors and resulted in significantly improved survival of tumor-bearing rats compared to those with intact sympathetic innervation. Using immunohistochemical methods, we found neuron-specific enolase immunopositive structures within fibrosarcoma tissue, indicating innervation of tumors. Finally, an in vitro study showed elevated proliferation of BP6-TU2 fibrosarcoma cells in response to adding norepinephrine to the culture medium. Our findings indicate that sympathetic nerves directly potentiate the proliferation of BP6-TU2 fibrosarcoma cells in rats.

Tumor interactions with soluble factors and the nervous system

In the genomic era of cancer research, the development of metastases has been attributed to mutations in the tumor that enable the cells to migrate. However, gene analyses revealed that primary tumors and metastases were in some cases genetically identical and the question was raised whether metastasis formation might be an inherent feature of certain tumor cells. In contradiction to this view, the last decade of cancer research has brought to light, that tumor cell migration, similar to leukocyte and fibroblast migration, is a highly regulated process. The nervous system plays an important role in this regulation, at least in two respects: firstly, neurotransmitters are known to regulate the migratory activity of tumor cells, and secondly, nerve fibers are used as routes for perineural invasion. We also summarize here the current knowledge on the innervation of tumors. Such a process might establish a neuro-neoplastic synapse, with the close interaction of tumor cells and nerve cells supporting metastasis formation.

PC-3 prostate carcinoma cells release signal substances that influence the migratory activity of cells in the tumor's microenvironment

BackgroundTumor cells interact with the cells of the microenvironment not only by cell-cell-contacts but also by the release of signal substances. These substances are known to induce tumor vascularization, especially under hypoxic conditions, but are also supposed to provoke other processes such as tumor innervation and inflammatory conditions. Inflammation is mediated by two organ systems, the neuroendocrine system and the immune system. Therefore, we investigated the influence of substances released by PC-3 human prostate carcinoma cells on SH-SY5Y neuroblastoma cells as well as neutrophil granulocytes and cytotoxic T lymphocytes, especially with regard to their migratory activity.ResultsPC-3 cells express several cytokines and growth factors including vascular endothelial growth factors, fibroblast growth factors, interleukins and neurotrophic factors. SH-SY5Y cells are impaired in their migratory activity by PC-3 cell culture supernatant, but orientate chemotactically towards the source. Neutrophil granulocytes increase their locomotory activity only in response to cell culture supernantant of hypoxic but not of normoxic PC-3 cells. In contrast, cytotoxic T lymphocytes do not change their migratory activity in response to either culture supernatant, but increase their cytotoxicity, whereas supernatant of normoxic PC-3 cells leads to a stronger increase than that of hypoxic PC-3 cells.ConclusionsPC-3 cells release several signal substances that influence the behavior of the cells in the tumor's microenvironment, whereas no clear pattern towards proinflammatory or immunosuppressive conditions can be seen.

On tumor innervation

The presence of nerve elements in tumors has been much written and argued recently. All the controversy can be divided into four controversial questions: 1) Can the presence of nerve elements in real tumors be proved at all? 2) Are the nerves demonstrated by some authors really newly formed or nerves surrounded by a tumor? 3) Are there nerves in all groups of tumors? 4) Are the newly formed nerves a necessary component of tumor tissue or are they only the result of regeneration caused by tumor infiltration into normal tissue?